With the increasing demands on fuel economy and safety of vehicles, detecting transmission neutral signals and then judging the running states of a vehicle as well as controlling corresponding assemblies based on the detected transmission neutral signals so as to reduce the energy consumption and improve the safety performance of the vehicle are increasingly concerned. A neutral position sensor is mainly used for detecting whether a motor vehicle is in neutral or at a gear, so that when the vehicle is in neutral, the state of an engine is adjusted to fulfill the purposes of energy conservation and emission reduction.
As shown in FIG. 1 and FIG. 2, a conventional position sensor sensing system includes a position sensor 40 and a magnet assembly, wherein the position sensor includes a magnetic sensing chip 41, the magnet assembly is installed on e.g. a transmission shaft 50, and the magnetic sensing chip 41 is installed at one side of the magnet assembly away from the transmission shaft 50. The magnet assembly and the transmission shaft 50 moves within a limited measuring length together, and can rotate approximately 25 degrees at each gear position. The magnet assembly includes a magnet bracket 10 and a magnet 20 arranged in the magnet bracket 10. The magnet 20 arranged in the magnet bracket 10 in the prior art generally adopts a cuboid structure. In such an arrangement, magnetic field intensity components Bz in the magnetizing direction z at two ends of the magnet along the sensing direction (the axial direction of the shift shaft) y are smaller than the magnetic field intensity components in the middle of the magnet due to the magnetic field edge effect. Consequently, the measuring length L sensed by the magnetic sensing chip 41 is relatively short (as shown in FIG. 2).
Hence, the magnet 20 should be long enough in the axial direction y of the transmission shaft to ensure that the magnetic sensing chip 41 can always detect accurate data. Such requirement results in that the magnet 20 occupies a large space and is high in manufacturing cost.